<!DOCTYPE html>
<html lang="zh-CN">
  <head>
    <meta charset="UTF-8" />
    <meta name="viewport" content="width=device-width, initial-scale=1.0" />
    <title>Document</title>
    <style>
      ul {
        list-style-type: none;
        background-color: red;
        /* display: inline-block; */
      }
      ul::after {
        content: "";
        display: block;
        clear: both;
      }
      ul li {
        float: left;
        background-color: red;
      }
    </style>
  </head>
  <body>
    <ul>
      <li>a</li>
      <li>a</li>
      <li>a</li>
      <li>a</li>
      <li>a</li>
    </ul>
    <div>33</div>
  </body>
</html>
